APPARATUS AND METHOD FOR PARTICLE CONCENTRATION AND SEPARATION IN A CLOSED FIELD

Abstract: A particle separator is provided for collection and manipulation of target particles, e.g., target cells, in a closed sterile field condition. In one embodiment, closed sterile field conditions are maintained from separation through concentration and/or cryo treatment steps and/or transfusion. Preservations of closed sterile field conditions are accommodated by using the same integrally coupled vessel for collection and concentration and transfer via integrally coupled conduits to a vessel for cryopreservation and/or transfusion. In one embodiment, a degree of cell concentration can be achieved, while maintaining closed field conditions, by using a hollow fiber device, preferably in-line between the column and the collection used. In another embodiment, a hollow fiber device is used in place of the column to achieve cell washing. In one embodiment, a plurality of valves are responsive to a data processor for controlling the path of fluid flow through the particle separator. A plurality of sensors are provided for providing sensor signals indicative of fluid flowing through the cell separator. A peristaltic pump is responsive to the microprocessor assembly for controlling the speed and direction of fluid flow through the system. A stir plate assembly is responsive to a signal from the data processor for controllably agitating the contents of the cell separator.

Description: APPARATUS AND METHOD FOR PARTICLE CONCENTRATION AND SEPARATION IN A CLOSED FIELD This application is a continuation-in-part of application Serial No. 08/052,784, for "Apparatus and Method for Particle Separation in a Closed Field" filed April 23, 1993, which is a continuation-in-part of application Serial No. 08/005,891 filed January 15, 1993, which is a continuation of USSN 07/780,750, filed October 23, 1991, now U.S. Patent 5,240,856, for "Improved Apparatus and Method for Cell Separation" all of which are incorporated herein by reference. The present invention is directed in general toward methods and apparatus for selecting target particles such as specific target cells from a heterogeneous population thereof in a sample fluid and, more particularly, toward improved apparatus for controlling the operation of a device for performing immunoselection and, preferably, concentration of target cells, preferably in a closed field. BACKGROUND OF THE INVENTION Various methods and devices exist for separating component parts of a sample fluid to obtain target particles such as cells. These methods include filters, centrifuges, chromatographs, and other well-known fluid separation methods. Other apparatus and methods exist for separating a particular cell subpopulation, or target cells, from a mixture of cells. These methods include gross separation using columns, centrifuges, filters, separation by killing of unwanted cells, separation with fluorescence activated cell sorters, separation by directly or indirectly binding cells to a ligand immobilized on a physical support, such as panning techniques, separation by column immunoadsorption, and separation using magnetic immunobeads. Such immunoselection methods have been used to either positively or negatively select target cells, wherein positive selection refers to the direct selection and recovery of specific target cells, while negative selection refers to the elimination of a specific target cell subpopulation from a heterogeneous population of cells. Columns are common to the above described methods for general separation of target particles, such as target cells, from a mixture of cells in a sample fluid, and for the more specific immunoselection methods for selecting target cells from a sample fluid. Typically, a column has an entrance end, an exit end, and a substrate positioned intermediate the entrance and exit ends. In operation, the sample fluid is provided to the entrance end of the column and is moved through the column under pressure. As the sample fluid passes through the column, the substrate binds a sub¬ population of cells from among the mixture of cells in the sample fluid so that the fluid exiting the column is fractionated with respect to the cell mixture. In one embodiment, the substrate separates the target particle from the fluid composition so that the target particle exiting the column will be substantially pure. The target cells flowing through the column can be collected and retained as the product of the separation. Alternatively, the flow-through can be discarded and the cells which are bound to the substrate can be eluted and collected. Accordingly, the substrate is chosen for a particular separation to separate the target particle (e.g., cells) from other particles contained in the sample fluid by a negative or a positive selection process. In many situations, it is preferred to avoid loss of target particles, such as cells. In some devices, the conduits or other flow paths along which the target cells travel contain relatively sharp (low radius of curvature) turns, or angled turns such as right angle turns. These configurations can lead to undesirable particle or cell loss. Various substrates exist for use with columns to separate the target particle from the sample fluid. Generally, the type of substrate chosen for performing the separation will determine how the target particles are separated from the sample fluid. As an example, in high- performance liquid chromatography (HPLC) , the sample fluid is forced through the column under pressure using a solvent solution. The substrate is chosen so that the target, particles exhibit substantially different binding characteristics with the substrate than the remaining components of the sample fluid so that the time necessary for the target particles to pass through the substrate will be substantially different from the time necessary for the remaining components of the sample fluid to pass through the substrate. Accordingly, a substantially pure composition of the target particles will exit the column at a predetermined time for collection. In reference to immunoselection methods utilizing immunoadsorption devices, a ligand, such as an antibody, may be immobilized on the substrate. For example, using a separation device such as a column immunoabsorption device, the substrate may contain beads that have been coated with a ligand, immobilized on the surface of the beads. The ligand is chosen to specifically bind the target particles, thereby immobilizing the target particles within the separation device. After an adequate amount of the fluid composition has been passed through the separation device, to remove unbound cells from the device and/or to saturate the substrate, the target particles can be liberated from the substrate using various techniques. In one embodiment, the target particles are liberated from the substrate (such as beads) by gently agitating the substrate to break the bond between the target particles and the immobilized ligand. Previous devices and methods have provided a degree of particle separation in a fashion which is not entirely contained in a closed field. In this context, closed field refers to a process and apparatus in which there is no exposure of the target particles to the environment between the time the sample containing the target particles is provided at the beginning of the method or apparatus and at least the time at which the target particles have been substantially separated. Previous devices and methods have also provided a degree of particle separation which is not entirely a sterile field. In one embodiment, the present invention provides particle separation in a closed field and, preferably, a sterile field. In one embodiment, the present invention provides a sterile field having fewer than a predetermined number of live micro-organisms per cubic centimeter. In one embodiment, closed field conditions, preferably sterile field conditions, are maintained beyond the time of particle separation, such as until particle concentration (such as by centrifugation or other means) cryopreservation, and/or reconstruction for infusion (which can involve, for example, addition of cryo media and/or cooling to cryogenic temperatures such as about -20° to -196° centigrade, as well as the resuspension of cells for transfusion after cryopreservation) . It is recognized that no procedure can provide a perfectly closed field or a perfectly sterile field in the sense that it is impossible to absolutely eliminate all exposure to the environment, such as exposure to all ambient molecules or radiation. In this context, closed field will be understood to mean substantially closed field, i.e., with sufficient protection from exposure to the environment to prevent the introduction or proliferation of microorganisms. For example, when the particles being separated are human stem cells for use in medical treatment, the apparatus and procedure should provide sufficient closed field characteristics that the separated stem cells are protected from exposure to potentially harmful aspects of the environment such as bacteria, viruses and other micro¬ organisms. In this example, exposure to ambient atmosphere via an appropriate filter, such as for eliminating contaminants with a size greater than about 0.22 microns, is substantially a closed field. Certain previous methods and devices have involved time-consuming or relatively expensive procedures. For example, certain devices require relatively complicated preparation or manipulation, such as involved insertion of tubing or other conduits, e.g., for the purpose of fluid transfer, or the requirement for preparing certain portions of the apparatus prior to introduction of the sample fluid, such as a protein loading requirement. Certain previous devices have included reusable apparatus which can come in contact with the target particles, thus either, requiring careful and extensive sterilization and/or risking contamination. In view of these items, it is desirable to provide a fluid separation apparatus which results in a substantially closed, preferably sterile field procedure for isolating target particles, at least through the separation stage and in some embodiments, through concentration and/or cryopreservation. It is desirable to provide an apparatus and method which is simpler, less error-prone and less time- consuming than previous devices and methods and has a reduced risk of contamination. Some devices for performing immunoadsorption have proven undesirable since they have failed to provide commercially acceptable apparatus for agitating the substrate to aid in liberating the target particles. Some devices have also failed to provide apparatus for controlling the amount of agitation provided to the substrate, to prevent damage to the target particles and are further undesirable for this reason. Separation devices, and particularly immunoadsorption devices, have also proven inefficient since these devices require considerable intervention from the operator to control the introduction of the sample fluid to the column as well as controlling the withdrawal of the target particle, such as cells, from the column. Typically, separation devices must be actively monitored through various stages including stages for cleansing the separation device prior to introduction of the sample fluid and for passing the sample fluid through the separation device. These stages generally require significant intervention from the operator to perform each of the foregoing steps of the fluid separation process, and to perform substeps within these steps. Accordingly, the efficiency of these devices is necessarily limited by the skill and effectiveness of the operator controlling the process. It is further desirable, therefore, to provide apparatus for performing fluid separation that minimizes the amount of intervention necessary from an operator of the apparatus. Additionally, it is desirable to provide apparatus for performing fluid separation wherein the movement of fluid through the apparatus may be precisely controlled by the separation apparatus without significant intervention by the operator. Among the substeps which sometimes require operator intervention are steps involved in concentration of the separated cells. Accordingly, one aspect of the invention involves including concentration of the separated cells while reducing or eliminating the need for operator intervention for such concentration, and preferably while maintaining a closed- field and avoiding cell loss or damage. Although a common use of cell separation is to separate a desired cell population from a mixed cell population, clinical and research procedures also often require separation of cells or other particles from other types of material such as antibody materials used in the initial preparation of the cell mixture. Previous approaches to this type of procedure have included use of a cell washing device and/or a centrifugation procedure. However, previous methods have typically incurred a high rate of cell damage or cell loss, often in the range of 25% to 40% cell damage or loss. Accordingly, it would be useful to provide a device that achieves washing or other separation of cells or other particles with a reduced loss of the cells or other particles, preferably while maintaining a substantially closed field. SUMMARY OF THE INVENTION The subject invention provides improved apparatus and method for separating target particles from a sample fluid containing the target particles mixed with other items, such as a liquid medium, and/or other cells or particles. In one embodiment of the present invention, an improved fluid control system is provided for use with a cell separation device assembly. In one embodiment, the separation device is a column separation assembly. Other types of separation devices are also possible, including hollow fiber devices, filters, single or multiple plates such as immunoabsorption plates (so- called "condo plates") and magnetic beads. In the embodiment depicted in Fig. 1, the cell separation device assembly includes a column 1002 for separating target cells from a sample fluid 1004. The cell separation device assembly also includes a fluid collection vessel 1006 for subsequently receiving the target cells from the column. The remainder of the sample 1004, i.e., the portion which is not collected in the target cell collection vessel 1006, is collected in a waste receptacle 1008. Valves 1010 are provided for controlling flow from the sample 1004 to the column 1002. Valves 1012 are provided for controlling flow from the column 1002 to the target collection vessel 1006 and waste receptacle 1008. The valves 1010 and 1012 are controlled using a controller 1014. The separation device 1002 can be any of a number of devices for selectively retaining target particles, including an immunoadsorption column. The valves 1010 and 1012 can be any of a number of devices for controlling flow and in some embodiments, are valves which operate without providing any contact with the target particles other than via sterile disposable components. The controller 1014 can be any of a number of controlling devices including mechanical controllers, pneumatic controllers, electronic controllers, optical controllers and the like. In one embodiment, the controller 1014 is an electronic controller, in one embodiment, a programmed digital processor. In one embodiment, the apparatus depicted in Fig. 10 achieves separation in a closed sterile field manner. Closed sterile field operation is particularly important when the cell separator is to be used in connection with an invasive procedure and especially when treating a patient with high susceptibility to infection, such as an immuno-compromised patient. A number of aspects of the apparatus and the method of operation contribute to the closed sterile field characteristics. One such aspect is that the entire fluid pathway from the sample container 1004 to the target collection vessel 1006 is closed or sealed from the environment; in one embodiment, preventing exposure to any environmental component having a size greater than about 0.22 micron. As described more fully below, in one embodiment the pathway includes a series of tubing conduits, filters and vessels, all of which are connected together so as to prevent exposure to the environment. This fashion of connecting- together to prevent exposure to the environment is referred to hereinafter as "integral connection," without intending that the connection must be formed by way of integrally-formed material. Furthermore, each vessel can be configured to permit coupling to other components in order to achieve the desired separation goal and is configured to permit access, preferably aspectic access, as may be used, for example, for concentration or cryopreservation purposes, without substantial exposure to the environment. For example, in one embodiment, the target collection vessel 1006 is configured to permit the same vessel which is used for a collection of target particles to be also used for concentration, such as centrifugation, and/or cryo treatment, thus making it unnecessary to breach the target collection vessel 1006 for transfer purposes. Another aspect contributing to the closed sterile field nature of the device involves providing all components which may contact the target cells as sterile, non-pyrogenic, single-use components. For example, the column 1002, as described more thoroughly below, is insertable into the apparatus in a modular fashion and is not used more than once. Similarly, the target collection vessel 1006 is used for single collection operation an is not reused with another sample. Similarly, the tubing or other conduits joining the various components are removed after a given operation of the apparatus and replaced with fresh, sterile tubing for use in separation of the next sample. In one embodiment of the invention, the suspension of separated cells, mixed with a liquid carrier which exits the cell separator 1002 is provided to a hollow fiber device for concentrating the cells prior to delivering the cells to the target collection vessel 1006. This configuration achieves concentration which, previously, had required operator intervention, such as by centrifugal sedimentation and aspirating-off separated fluid. By placing the concentrator device in-line, as part of the overall automated separation device, concentration can be included in the procedure while preserving closed-field conditions. In one embodiment of the device, the apparatus is configured for a cell washing procedure by using a hollow fiber device in place of or addition to the column 1002, e.g., as depicted in Fig. 3. This embodiment, described more fully below, provides for cell washing with a relatively low rate of cell damage or loss and preferably while maintaining closed- field conditions throughout the cell washing procedure. Preferably, some or all of the same apparatus can be used for the cell washing, depicted in Fig. 3 and the cell separation, depicted in Figs. 1 and 2, e.g., by replacing the hollow fiber device 3014 with a column device 1002. This provides for conservation of resources and materials and minimizes training requirements. In one embodiment, the column 1002 is provided already-loaded with a substrate suspended in a stabilizing (protein-containing) buffer. In this way, it is not necessary to perform a protein-loading operation after installation of the column 1002 into the device. A separation device with a column pre-loaded with substrate in a stabilizing buffer eliminates the need for the operation or facilities to breach the closed sterile field in order to introduce or exchange buffers, consequently eliminating the attendant risk of system contamination. This configuration also simplifies the procedure, and apparatus, reducing the potential for error and resulting in a more rapid procedure. In one embodiment of the invention, undesirable cell loss is avoided or eliminated by eliminating or reducing the number of occurrences of sharp (small radius of curvature) conduit curves or angles or providing curves having a larger radius of curvature compared to previous configurations. In one embodiment the fluid control system includes a sensor for providing a first signal indicative of the optical density of fluid flowing out of the separation device and into the fluid collection bag. The fluid control system also includes a valve responsive to a control signal for selectively enabling the fluid flowing from the separation device to enter the fluid collection vessel. A data processor, such as a microprocessor, is provided for controlling the operation of the fluid control system. The processor is responsive to the first signal for providing the control signal to optimize the concentrations of the target cells being collected. In one embodiment the separation device assembly includes a sample fluid supply vessel (such as a bag) for providing the sample fluid to the separation device and fluid tubing for coupling the separation device to the sample fluid supply vessel and the fluid collection vessel. The fluid control system further includes a pressure sensor coupleable to the separation device for determining the pressure of the fluid in the separation device. The pressure sensor includes a connector for coupling a pressure signal to the processor. A pump is provided and is responsive to a pump control signal for controlling the speed and direction of fluid flow in the fluid tubing. The processor is responsive to the pressure signal for providing the pump control signal to increase and decrease the pressure of the fluid in the separation device. In one embodiment, a cell separator is provided that includes a separation device assembly for separating target cells from mixture of cells in a sample fluid. The cell separation device assembly includes a column, a sample fluid supply vessel, and a fluid collection vessel wherein the column is provided for receiving the sample fluid from the sample fluid supply vessel and for separating the target cells from the sample fluid and retaining the target cells. The fluid collection vessel is provided for subsequently receiving the target cells from the column. The cell separator includes an agitation assembly for agitating the contents of the cell separation device to assist in the release of target cells retained in the device. The agitation assembly is responsive to a drive signal for varying the amount of agitation of the contents of the separation device to vary the rate at which the target cells are released. The cell separator also includes a sensor for providing a signal indicative of the optical density of fluid flowing out of the separation device and into the fluid collection vessel. Further, the cell separator includes a valve that is responsive to a valve control signal for selectively enabling the fluid coming out of the separation device to flow into the fluid collection vessel. A processor is provided for controlling the operation of the cell separator. The processor is responsible for providing the drive signal and the valve control signal to prevent inadequate concentrations of the target cells from being collected. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic block diagram of a separation apparatus according to an embodiment of the present invention; Fig. 2 is a schematic block diagram of a separation apparation according to another embodiment of the present invention; Fig. 3 is a schematic block diagram of a cell washing apparatus, according to one embodiment of the invention; Fig. 4 is a schematic block diagram of an apparatus according to an embodiment of the present invention; Fig. 5 is a schematic block diagram of a separation and concentration apparatus according to an embodiment of the present invention; Fig. 6 is a diagram of a fiber of a hollow fiber device; Fig. 7 depicts a collection vessel, waste and freezing base and centrifuge cup according to an embodiment of the present invention; Fig. 8 depicts a freezing cassette, according to an embodiment of the present invention; Fig. 9 is a plan view of a target collection vessel according to an embodiment of the present invention; Fig. 10 is a perspective view of an apparatus according to an embodiment of the present invention; • Fig. 11 is a front elevational view of an apparatus according to an embodiment of the present invention; Fig. 12 is a flow diagram of a procedure according to an embodiment of the present invention; Fig. 13 is a flow diagram of a procedure according to an embodiment of the present invention; Fig. 14 is a flow diagram of a procedure according to an embodiment of the present invention; Fig. 15 is a flow diagram of a procedure according to an embodiment of the present invention; Fig. 16 is a side elevational view of a magnetic stirrer drive mechanism according to one embodiment of the present invention; and Fig. 17 is a top plan view of the drive mechanism of Fig. 16. DESCRIPTION OF THE PREFERRED EMBODIMENT As illustrated in Fig. 4, fluid inputs to the separation device 1002 include the sample input 1004 and one or more wash fluid inputs 1122. Fluid outputs are received in the target collection vessel 1006 a used wash container 1124 and a waste vessel 1008. The wash fluid 1122 can be input, if desired, through an optional filter such as a 0.22 micron filter 1126. One example is filter number IV-3 produced by Gelman Sciences. The flow of output from the sample container 1004 is sensed by a sensor device 1128. A number of fluid sensors can be used. In one embodiment, the sensor does not contact the fluid, in order to maintain a closed preferably sterile field condition. In one embodiment, an optical density or refraction sensor is used. One such sensor is described in U.S. Patent No. 5,240,856. Information from the sensor 1128 can be used for controlling flow such as by controlling valves 1010, 1012. Preferably, the output from the sensor 1128 does not directly control the valves 1010, 1012, but instead, provides one of the inputs 1130 to the controller 1014 which, in turn, provides output control signals 1132 for controlling, among other things, the valves 1010, 1012. Employing the controller 1014, rather than directly controlling the valves 1010, 1012 with the output from the sensor 1128, provides greater flexibility and accuracy of control. For example, although a decrease in optical density of the fluid exiting the sample vessel 1004 can be used as an indication of a near-empty state of the sample vessel 1004, a decrease in optical density can also be caused by, for example, bubbles or other discontinuities in the flow. The controller 1014 can be used to distinguish between these two conditions, e.g., on the basis of duration of the change in optical density, or on the basis of the time at which the discontinuities occur (e.g., near the beginning or near the end of the predicted flow from the sample container 1004) . Thus, in one embodiment, the user can input the volume of the sample using the keyboard 1134 to enable the controller 1024 to, e.g., suspend checking for flow discontinuities until most of the sample 1004 has had time to leave the container. In one embodiment of the invention, the controller comprises a personal computer as is commercially available. The flow leaving the sample 1004 can be passed through a partial filtration device for removing unwanted components such as large particles which might clog the separation device. As used herein, a filtration device is a device for at least partially excluding components larger than a given size. In one embodiment, the filtration device can be a gel. In one embodiment, a pre-column is provided for pre- filtering the sample fluid prior to the fluid separation to remove large particles and debris from the sample fluid. It is also possible to use both a pre-column containing a gel and a filter. In the embodiment of Fig. 11, however, the filtration device is a filter 1136. The filter is configured to prevent passage of materials having a size greater than the effective size of the passageways in the separation device. In one example, a filter having passageways of about 0.40 micron is used. One example of such a filter is Model SQ405 produced by Pall Biomedical. As described more fully below, one or more valves 1010 control flow from the wash 1122 and sample 1004 into the column 1002. The valves 1010 are controlled by the output control signals 1132 from the controller 1014. In one embodiment, each of the valves includes a solenoid and plunger separated by a valve channel sized to receive the fluid tubing. Each valve is responsive to a respective valve control signal for displacing the plunger to fully or partially collapse the fluid tubing and thereby prevent or control the flow of fluid through the valve. The plurality of valves are positioned to receive respective portions of the fluid tubing, thereby to define a plurality of fluid flow paths. The data processor assembly is constructed to provide the plurality of valve control signals for controlling the path that the fluid flows through the fluid tubing. As described more fully below, the column 1002 is substantially sealed from the environment and has an input port and an output port coupleable to provide closed (i.e., integrally coupleable) field flow of the sample fluid into and out of the column 1002. The column 1002 includes a substrate which is configured to selectively adsorb and controllably release the target particles. In one embodiment, release of the target particles is at least partially achieved using mechanical agitation. In this embodiment, such mechanical agitation is preferably provided without the need to breach the column vessel 1002 and, in one embodiment, a magnetically- coupleable stirrer is provided in the column 1002. The stirrer can be magnetically coupled in the stirplate 1142, which is controlled by the controller 1014. It is possible to provide a mechanical coupling to the column stirrer but preferably any coupling is done so as to maintain the closed field condition. With reference to Figs. 16 and 17, in one embodiment the stirplate assembly includes a housing having mounted therein a rotating table assembly 1904 for generating a moving magnetic field. More particularly, the table assembly comprises a substantially flat circular magnet table 1904 having mounted thereon first and second magnets 1906 and 1908. The magnet table is mounted upon a bearing assembly that rotatably supports the magnet table 1904. The stirplate further includes an electric motor 1912 mounted exterior to the stirplate housing. The stirplate assembly also includes a positioning portion mounted to the exterior of the housing on the top thereat for fixedly receiving the column. Further, the column includes an agitation assembly that is responsive to the moving magnetic field created by the stirplate assembly for agitating the contents of the column. The column bottom has an opening for connection to tubing 1762. The tubing 1762 passes through a hole in the center of the magnetic table 1904 and thus, in the depicted embodiment, through the general region of the time-averaged magnetic field which occurs upon rotation of the magnetic table 1904. Providing for passage of the tubing directly downward from the column bottom 1904 avoids the curving of the conduit that would be required if the conduit had to be routed around the periphery of the magnetic table 1904. Avoiding such curving is helpful in avoiding the type of cell loss associated with a sharply curved or angled conduit, as discussed above. Preferably, sharp curves having a radius less than about 1/2", preferably less than about 1" and more preferably less than about 1 1/2" are avoided in the pathway for target cells after they leave the column. This aspect of the invention is particularly important in situations in which the magnetic table magnets must be located relatively close to the bottom of the column since a curving conduit, in this situation, would have to be sharply curved or angled, to accommodate the small height necessitated by a close proximity of the table magnets with the stir bar magnets. In the depicted embodiment, the threading of the conduit 1762 through a hole is avoided by providing a magnet table 1904 that includes a slot 1952. In this way, the user, rather than have to thread the conduit 1762 through a hole, can insert the conduit laterally through the slot 1952 to the desired location 1954 in the center of the magnet table 1904. Preferably, the data processor assembly is configured to provide a drive signal which, responsive to a position sensor such as optical encoder 1934 and encoding wheel 1936, will assure that whenever the magnet table 1904 is stopped it will be aligned substantially in the configuration depicted in Fig. 20 with the slot 1952 positioned to permit easy access by the user for insertion of the conduit 1762. To avoid the drive belt interfering with insertion of the conduit, in the depicted embodiment 1918 is coupled to the perimeter of the magnet table 1904 along a portion of the outside edge of the drive belt 1918, so that the drive belt 1918 rests against the periphery of the magnetic table 1904 which is spaced from, and preferably opposite to, the position of the slot 1952 when the table 1904 is stopped in the preferred position depicted in Fig. 17. Thus, in the configuration of Fig. 17, if the belt moves in a clockwise direction the table 1904 moves in a counterclockwise direction. In the embodiment depicted in Fig. 17, the belt 1918 is driven by a drive wheel 1914 connected by a shaft 1916 to a motor 1912, such an electric motor, preferably a stepper motor. The belt 1918 is held in the desired configuration by a plurality of idler wheels 1956a-1956d. In the depicted embodiment, magnet table 1904 includes a groove 1958 on its periphery for accommodating a portion of the drive belt 1918. The portion of the magnet table 1904 which is spaced from the drive belt 1918 is guided by guide wheels 1962a-1962d, preferably configured to correspond to the grooved periphery surface of the magnet table 1904. Data regarding the measured rate of agitation is provided from the stirplate 1142 to the controller 1014. The controller 1014 provides output signals 1132 used in setting and modifying the amount of agitation. In one embodiment, the column vessel 1002 is pre- filled with a stabilizing buffer containing a protein such as human serum albumin (HSA) . Because it is desired to avoid contamination of the target particles, the column pre-filled with substrate and stabilizing buffer, in one embodiment, is sterilized. Means of sterilizing the pre-filled column include, e.g., steam and dry heat. In many cases, some period of time (e.g. , 12-30 months) may elapse between the preparation of the separation device and its use for separation. Preferably, the sterilized protein is stable over this period or longer. It is also possible to provide a separation device which does not initially contain a stabilizing buffer and to load the separation device with stabilizing buffer after the column is installed in the apparatus 1102. The apparatus depicted in Fig. 11, wherein the separation device is pre¬ loaded with stabilizing buffer requires fewer source vessels, reduces the risk of introducing contaminants to the fluid system, enhances performance of the separation device, requires a shorter time to achieve the desired separation, and results in a device which is believed to be simpler to operate and more cost-effective. A sensor 1144 is provided to sense or measure flow out of the separation device 1002. Output from the sensor 1144 is provided as one of the inputs 1130 to the controller 1014. A pump 1146 is used to establish a desired direction and rate of fluid flow. Although it is possible to provide fluid flow without using a pump, such as by using gravity, a pump 1146 provides desirable control at a reasonable cost. Preferably, the pump 1146 operates while maintaining the closed, preferably sterile field condition and, in one embodiment, a peristaltic pump is used. The controller 1014 provides an output signal 1132 for establishing the direction and speed of the pump 1012. The peristaltic pump, in one embodiment, provides a pump speed signal to the data processor. The pump speed signal is indicative of the speed and direction that fluid is being pumped through the fluid tubing. An appropriate peristaltic pump for performing the above-described operation may be readily constructed by one skilled in the art. In one embodiment of the invention, the peristaltic pump comprises a Cavro 4708-5 peristaltic pump as provided by Cavro Scientific Instruments, Inc. (Sunnyvale, California) . It will be apparent, however, that other apparatus for providing the functions of the peristaltic pump may readily be substituted for the Cavro pump. The target collection vessel at 1006 is coupled to the remainder of the apparatus in such a way as to be able to receive the target particles while maintaining a desired closed, preferably sterile field condition. In the embodiment of Fig. 4, the target collection vessel 1003 is coupled via valves 1012 to the output of column 1002. In one embodiment, however, it is desired to also provide a concentrator, preferably in-line between the output of the column 1002 and the collection vessel 1006, as depicted in Fig. 5. If no concentrator is provided, the output of the column 1002, in a typical application of the apparatus will be relatively large. For example, when the apparatus is used for separation of human stem cells, the apparatus may yield as much as 80 to 90 ml of suspension, or more. Such a large volume yield presents certain difficulties. For example, this volume is typically too large to contain in a single centrifuge vessel of the type often used for centrifuging the suspension of separated cells. Accordingly, the yield is often split into two or more centrifuge vessels which increases the amount of handling and the number of vessels used. It is found that increasing handling and the number of vessels used often results in damaged or lost cells, as well as increasing the risk of contamination. Accordingly, the embodiment depicted in Fig. 5 provides for a concentrator, such as a hollow fiber device 2014 which can be connected in-line for concentrating the separated cells and thus reducing the volume of material that is to be collected in the target collection vessel 1006. Hollow fiber devices generally are composed of a bundle of substantially parallel fibers, such as the fiber 6012 depicted in Fig. 6. Each of the fibers 6012 is generally in the form of a long cylinder made up of a porous membrane 6014. The pores are of a size and density to provide a desired separation function. In the present application, the bundle of fibers receives a flow which is a suspension of the target cells in a fluid carrier 6016. The pores are of a size and density such that some of the carrier fluid exits across the membrane 6018 through the pores while the target cells travel through the lumen of the fibers and out the distal end of the fibers, suspended in a reduced volume of fluid- 6022. A number of parameters of the hollow fiber device and of the environment in which it is operated affect the performance of the device. Among these parameters are the fiber material, the pore size and pore density of the fibers, the lumen diameter of the fibers, the bundle diameter of the fiber bundle, bundle length, the in-line pressures, (i.e., P in and P out ) and the in-line pressure drop (i.e., P in _ line = P in - P out ) the transmembrane pressure drop ΔP trans , the cell concentration of the suspension and the viscosity of the suspension. Table I lists hollow fiber parameters and indicates approximate preferred, more preferred and most preferred ranges for various parameters that may be used in various applications. The fiber material can also be polypropylene. Table I — Approximate Parameters for Cell-Concentration Although hollow fiber devices have been used for other applications, such previous applications were believed to have significant differences in the parameters since they were directed to applications having different goals and problems. Among previous applications of hollow fibers were plasmapheresis and dialysis. One of the difficulties encountered in dialysis is the need to maintain a flow rate which is as high as possible at all times (in order to make the dialysis process rapid enough to be tolerated and useful) . Accordingly, dialysis hollow fiber procedures typically require the use of a monitor device and an associated feedback procedure in which the status of the procedure is monitored, for example, to detect the transmembrane pressure differential, and/or such factors as hollow fiber fouling such that when an excessive pressure is detected or an increase in loading is detected, the device is controlled to reduce the transmembrane pressure. Once these factors fall below a predetermined threshold, the transmembrane pressure is again increased. In the present application, in contrast, the need for high flow rate and high throughput is less critical and a relatively lower input flow rate (e.g., 10 to 20 milliliters per minutes is used as opposed to a typical dialysis flow rate of 150 to 200 ml per minute) . Furthermore, the present device can be operated at fixed values, i.e., without the need for a monitor and feedback to continuously change values, such as transmembrane pressure values, to maintain them at an optimal or highest workable value. Although the concept of using substantially fixed values such as a substantially fixed transmembrane pressure provides the advantage of simplicity of apparatus, design and operation, this approach is not without its own problems. One of the problems arises from the fact that the operating parameters of the device change in time, e.g. , as the fibers experience some degree of fouling and/or as the concentration, viscosity, or other parameters of the suspension change. In some cases, these changes in operating parameters result in a change in response of the device itself. Accordingly, it is difficult to design an apparatus which will operate at fixed values, but which will provide acceptable performance during changing conditions of a separation run, such as changing cell concentration, viscosity, fiber loading and the like. Another difference between a typical dialysis fiber application and the present application is the common practice in dialysis of providing a dialysate, such as is available from Baxter and Abbott, between the fibers to create an osmotic pressure to assist in the dialysis process. In the preferred embodiment of the present invention, a dialysate is not used and there is no substantial reliance on osmotic pressure for creating a transmembrane pressure differential. Another difference between these processes is that dialysis applications operate on a fluid, (i.e., blood) which has a higher viscosity than the typical viscosity of the applications contemplated in the present invention (e.g., saline) . Another difference is the presence of platelets in the blood being treated by a dialysis device which contribute to fiber fouling. There will typically be few, if any, platelets in the suspension used in the present invention for the presently contemplated applications. Another difference is the molecular weight cutoff. In typical dialysis hollow fiber device, the molecular weight cutoff is often in the range of about 60 to about 90 KD (kilo Daltons) . As seen from Table I, the present invention provides a pore size in the range from about 0.2 to about 0.1 microns and a molecular weight cutoff in the range of 10-50 KD. Another difference is that dialysis hollow fibers have a relatively small fiber diameter, often in the range of about 50 microns, while the fibers used in the present invention involve size of about 0.5 mm to about 0.6 mm, for many of the presently contemplated applications. In one embodiment, the fiber bundle used is Model X11M-100-20N available from Microgon. As depicted in Fig. 5, the valves 1012 are configured by the controller 1014 to direct the concentrated cell suspension 6022 to the target collection vessel 1006 and to direct the separated fluid 6018 to a waste receptacle 1008. In one embodiment, the separation is achieved primarily by creating a low pressure outside the fibers in order to achieve the transmembrane pressure 6024 while the in¬ line pressure drop is allowed to "float". In one embodiment, the pump 1146 is used indirectly to supply a low pressure external to the fibers, preferably by using tubing 5012 to connect the pump 1146 to the exterior of the fibers 2014 which has a sufficiently small diameter that the supplied pressure has the desired value. The device depicted in Fig. 5, accordingly, is able to achieve a collection of separated cells in a relatively concentrated form, such as in a volume of about 5 to 20 ml compared to 80 to 90 ml of suspension which was typical of collection without using a concentrator 2014. Because the hollow fiber device 2014 is placed in-line in the same apparatus that achieves the separation, the concentration is provided without significant operator intervention and while maintaining substantially closed-field, preferably sterile field conditions. In one embodiment, the invention can be used in connection with a cell washing procedure. For example, in one embodiment, it is desired to remove antibodies from a suspension that has resulted from incubating cells with certain antibodies. Previous washing procedures and/or antibody removing procedures such as the Cobe Cell Washer, Model Spectra, or a procedure of centrifugation have been used previously. However, previous devices and methods for cell washing have not been entirely satisfactory. These procedures typically require use of additional apparatus and thus require a capital investment in, for example, a cell washing device or a centrifuge in addition to investment in, e.g., a cell separator. Many previous devices have been subject to high cell loss or damage, such as 25% to 40% or more cell loss or damage. Many previous procedures and devices required substantial operator intervention or control, substantial transfer of materials between vessels and/or did not provide substantially closed-field conditions. According to the present invention, a hollow fiber device can be used in connection with cell washing. According to one embodiment, the same apparatus depicted in Figs. 10 and 11 can be used in cell washing by the simple expedient of replacing the column 1702 with a hollow fiber device 3014 and, preferably, including a feedback tubing line 3024. According to this embodiment of the invention, a controller 1014 controls valve 3010 to convey both the cell/antibody suspension 3004 and a wash fluid 3022 to the hollow fiber device 3014. The hollow fiber device 3014 is selected to permit passage of the target cells through the lumen of the fibers while drawing off the antibody material and wash fluid through the pores of the fibers. The controller 1014 controls the valves 3012 to direct the waste material (i.e., the materials which move through the pores of the fibers) to the waste receptacle 1008. The washed material, i.e., the material exiting from the fiber lumens, can be directed by the valves 3012 to the waste vessel 1008. However, in one embodiment, it is preferred to initially recycle the wash material via tubing line 3024 back to the input valve 3010 so that it can be reintroduced to the hollow fiber 3014 for additional washing. The amount of time used for recirculation, or number of recirculations that occur will depend upon a number of factors including the relative concentration of cells and antibodies in the suspension 3004. In one embodiment, it is contemplated that the cell/antibody mixture 3004 will be recirculated, on an average, about 5-50 times before being eventually directed by the valves to the target collection vessel 1006. The pressure and other parameters used for cell washing are not necessarily the same as the preferred parameters, noted above, for cell concentration. Table II sets-out parameters that are preferred for the cell washing embodiment of the invention. Table II — Parameters for Cell-Washing It is currently believed that, using this procedure, effective washing can be achieved while decreasing cell loss and/or damage to approximately 10% to 15%. The procedure for cell washing achieves the washing using an automatic apparatus, and preferably using an apparatus which can also be used for other purposes such as cell separation, e.g., the apparatus of Figs. 10 and 11, thus minimizing equipment expeditures, training, spare parts, inventory and the like. In one embodiment, the closed, preferably sterile field condition which has been achieved, is extended through the particle pelletizing or other further concentration step. In one embodiment, this is achieved by using the same vessel for both target cell collection and centrifugation. Using the same vessel has a number of advantages. It eliminates the step of transferring from one vessel to another which saves time and reduces the potential for error or introduction of contamination and also eliminates the loss of any residual particles which might resist transfer by adhesion to the surfaces of the vessel. Furthermore in many previous procedures, the target collection vessel was breached (such as by cutting or otherwise opening a collection bag) in order to transfer to a centrifugation vessel, thus violating or seriously degrading the closed field condition. In order for the same vessel to be used for collection and centrifugation, the vessel must be configured to be compatible with the centrifugation process. It has been found that it is possible to perform a certain degree of cell concentration using collection vessels which are flexible plastic bags. However, centrifugation using plastic bags has not been entirely satisfactory. It has been found that, using such bags, the separated cells have a tendency to wick up the side of the bag during expression of supernatant, interfering with the desired concentration and/or resulting in loss of cells. It has also been found that, during centrifugation, cells tend to fall into wrinkles formed in the bag making them difficult to concentrate and/or retrieve. Additionally, it has been found that when centrifugation is performed using a flexible bag, there tends to be an amount of residual fluid in the bag and it has been impossible to aspirate or otherwise remove substantially all of the fluid. Because of this, it is difficult to accurately determine the amount of residual fluid in the bag and thus it becomes difficult or impossible to calculate the proper amount of cyropreservative which should be added to the bag. Thus, although flexible collection bags provide the advantages of being relatively light, inexpensive and easily packaged and of being able to expand and contract to accommodate the fluid contained (thus eliminating or reducing the need for a vent) these aspects are believed to be outweighed, for most purposes, by the lack of repeatability and safety and the difficulty in concentration or pelletizing experienced in centrifuging flexible bags. Thus, according to one aspect of the invention, the vessel which is used for both target cell collection and centrifugation is a rigid vessel. Fig. 7 depicts a target cell collection vessel 7012 coupled to an associated waste bag 7014 and freezing bag 7016 and a centrifuge cup 7018 configured to accomodate the vessel 7012 and bags 7014, 7016. In the depicted embodiment, the vessel 7012 is a tube having a tapered lower portion which has the upper end substantially sealed. Tubing 1764 receives the output from the valves 1012. A first port in the sealed upper surface of the vessel 7012 is connected to a filter 7020, such as a 0.22 micron filter, for venting purposes, i.e., for expelling the contents, (e.g., gaseous contents) of the vessel 7012 when the vessel is being filled and for permitting entry of filtered ambient air or other gas into the vessel 7012 when fluid is being emptied from the vessel. A second port preferably sealed by a septum 7022 can be used for adding materials such as heparin and human serum albumin (HSA) and/or for removing samples, or removing separated and/or concentrated cells and/or for adding cryomedia. A third port in the sealed upper surface of the vessel 7012 is connected, preferably permanently, (i.e., without user-manipulated connectors) to tubing 7024 attached to the waste bag 7014 and freezing bag 7016. By providing the permanent connection 7024 to the freezing bag and waste bag, it is possible to transfer the waste and concentrated cells to the waste bag and freezing bag respectively in a manner which is easy to achieve, does not require insertion of needles or other devices into the vessel, and which does not require manual connection of bags to the vessel, such as by an operator. Because the bags 7014, 7016 are permanently connected to the vessel 7012, one aspect of the invention includes accomodating the bags during centrifugation. Typically, a centrifuge uses a cup device for holding a collection tube or other vessel in a well of the centrifuge. In the embodiment depicted in Fig. 7, the centrifuge cup 7018 includes not only a receptacle 7026 for receiving the vessel 7012, but also a receptacle 7028 for receiving the bags 7016, 7014. In the embodiment of Fig. 7, the receptacle 7028 is a slot formed in the cup 7018. Preferably, the slot 7028 has a size and shape to accomodate the bags 7014, 7016 after they have been folded, e.g., as shown in the phantom lines 7030. Other devices for holding the bags can be used such as a clip, coupled to the cup 7018, an envelope, a latch, and the like. Because cell loss or damage is often positively correlated with length of tubing through which the materials flow, the apparatus is preferably configured to minimize the length of tubing 7024 such as by placing the bag receptacle 7028 relatively close to the vessel receptacle 7026. In operation, the cells are collected into the vessel 7012 from tubing 1764. Preferably, at this point, a sample which is a 1 ml sample is collected through septum 7022. The vessel 7012 is placed into the vessel receptacle 7026 of the centrifuge cup 7018 and the bags 7016, 7014 are folded 7030 and placed into a receptacle 7028. The centrifuge cup 7018 is then placed in the centrifuge and the centrifuge is used to concentrate or pelletize the cells. The vessel 7012 and bags 7014, 7016 are removed from the cup 7018. The waste bag clip 7032 is moved to an open configuration and the operator will raise and tip the vessel 7012 in a "pouring" motion to pour the supernatant fluid into the waste bag 7014. The clip 7032 is then moved to the closed position and the freezing bag clip 7034 is moved to the open position. The cell pellet is resuspended. Preferably, 5 ml of cryomedium is also added via septum 7022 and the resulting suspension of cells and cryomedium is poured into the freezing bag 7016. The vessel 7012 may be rinsed, e.g., with another 5 ml of cryomedium and the resulting rinse of cells in cryomedium poured into the freezing bag 7016. The clip 7034 is then moved to the closed position. At this point, the freezing bag 7016 can be removed from the remainder of the apparatus of Fig. 7 (e.g., by cutting tubing 7024) so that the collected cells can be frozen. Previous freezing operations have had certain difficulties. Among these is the difficulty of adhering labels to the freezing bags when the bags are subjected to cryogenic temperatures, particularly in a liquid medium such as submersion in liquid nitrogen. Accordingly, the freezing bag 7016 is provided with a pocket 7036 for holding a label to identify the contents of the freezing bag 7016. Before placing in the cryogenic environment, the freezing bag 7016 is preferably placed in a freezing cassette device 8012 such as that depicted in Fig. 8. The depicted cassette has a platform 8014 for supporting the freezing bag and a cover 8016 hinged to the cassette 8018 so as to provide a cover over the freezing bag when lowered 8020 towards the closed position. Preferably, the cover 8016 has a window 8022 formed therein positioned to expose the pocket 7036 of the freezing bag and thus to display the identifying information contained in the pocket. The cassette 8012 includes a pocket region 8024 to accomodate tubing and/or valves or other protusions 7038 extending from the freezing bag. The top wall of the pocket 8024 includes an opening 8026 for accomodating, for example, a temperature probe. The freezing cassette is preferably constructed of a metal such as stainless steel. Fig. 9 depicts another embodiment of a collection vessel. As depicted in Fig. 16, in one embodiment the target collection vessel is a rigid-walled tube 1602. To assist in the centrifugation process, at least a portion 1604 of the tube 1602 has a concave or tapered configuration tapering from a larger cross-sectional area to a smaller cross-sectional area. In the depicted embodiment, the tapered section generally has the shape of the frustum of a cone. The vessel 1602 is substantially sealed from the environment. In the embodiment of Fig. 16, the vessel includes a cap 1606 having at least first and second ports. A first port 1608 is connected to a filter 1610, such as a 0.22 micron filter, for venting purposes, i.e., for expelling the contents (e.g., gaseous contents) of the vessel 1602 when the vessel is being filled and for permitting entry of filtered ambient air or other gas into the vessel 1602 when fluid is withdrawn from the vessel. A valve such as a slide clamp 1612 can be provided for opening or closing the port 1608. In the depicted embodiment, a second port 1614 is coupled to a three- way connector 1616. In this embodiment one arm of the three- way connector 1618 is a secondary port sealable by a septum or other resealable filament 1620 and can be used, for example, for adding cryomedium to the vessel prior to cryotreatment. A second arm is a secondary port sealed by a septum 1622 and can be used for adding materials, such as heparin and human serum albumin, removing samples or removing separated and/or concentrated cells. The third arm 1624 can be connected to tubing for coupling to a second 2-way connector 1626. The two-way connector 1626 includes one branch 1628, which is a tertiary port sealable by septum or other resealable filament 1630, e.g., for withdrawing supernatant fluid by aspiration. The other branch 1632 can be used, for example, as a tertiary port for connection to the separation apparatus 1102 for target particle collection. In the depicted embodiment, the second port 1614 is coupled to the interior of the vessel 1602 by a conduit 1634 so that fluid which flows in and out of the port 1614 enters and exits the vessel 1602 at a location 1636 which is spaced from the location 1638 where the vent port 1608 communicates with the interior of the vessel 1602. By providing a plurality of ports and/or connectors, the vessel 1602 can be used in a number of procedures, including collecting target particles, aspirating supernatant fluid, adding protein, removing target cells, adding cryomedia, and transferring to a storage vessel, such as a cryotube, while maintaining a substantially closed, preferably sterile field environment and without the need to perform a transfer from one vessel to another. It could be possible to perform a number of operations through a single port, such as a septum-covered port. However, reliability and confidence in freedom from contamination is enhanced by avoiding multiple reuse of a septum or similar resealable device. The vessel 1602 can be made of a number of materials. In one embodiment, injection molded polycarbonate is used, which is believed to provide a desirably low cytotoxicity. Other materials which can be used for the vessel include polystyrene, polyacrylate, other plastics and resins, glasses, ceramics and composite materials. Fig. 10 depicts an apparatus according to one embodiment of the invention. In Fig. 10, phosphate-buffered saline (PBS) solution is provided in a flexible bag 1722 as a wash source. The solution is provided through tubing 1752 and valves 1710a to the separation device 1702. In one embodiment, depicted in Fig. 11, the solution is provided through tubing 1752 via a filter 1826. The tubing is preferably sterile flexible plastic tubing. One example is available under the trade name "Tygon." The sample, which can be, for example, human bone marrow or peripheral blood, is provided, e.g., in a flexible bag 1704 through a sensor 1728 and a filter 1736 via a valve 1710b to the column 1702 via tubing 1754, 1756. The separation device is magnetically coupled to a stirplate 1742. Outflow from the separation device 1702 passes through a sensor 1744 and, via tubing 1762, to peristaltic pump 1716. Valves 1710c, 1710d, 1710e and 1710f control flow from the wash bag 1722 to the pump 1716 and from the pump 1716 to the tubing 1764, 1766, 1768 for connection to the target collection vessel 1006, wash bag 1124 and waste bag 1008, respectively. As illustrated generally in Fig. 12, the separation procedure begins with setting up the apparatus by installing the disposable or modular components 1202. This includes installing the tubing 1752, 1754, 1756, 1762, 1764, 1766, 1768, the filters 1726, 1736 and the separation device 1702 and by mounting and spiking the bags and vessels 1722, 1704, 1006, 1124 and 1008. In the next step, e.g., under control of the controller 1014, the newly-installed tubing filters and separation device are cleaned and washed such as by flushing with wash solution to remove contaminants and wash excess protein from the protein-loaded separation device 1204. One operable washing procedure is described more fully below. After the washing procedure is finished, the column 1702 is exposed to the sample solution 1704, e.g., using a slow-load procedure, described more fully below 1206. After the column loading procedure is finished, the column is washed 1208, also under control of the controller 1014 and eluted 1210 to recover the target particles. Advantageously, the stirplate assembly cooperates with the column to provide controlled agitation to the contents of the column. Accordingly, after a sufficient quantity of the target cells have been retained within the column, the target cell-ligand bond may be broken, in one embodiment, by controllably agitating the contents of the column. Thereafter, the target cells may be eluted from the column and collected as the product of the separation. In one embodiment, the suspension of target particles are provided to the target collection vessel directly. In another embodiment, the cells are first concentrated 1212, e.g., using a hollow fiber device, as depicted in Fig. 5. The following procedures depend partly upon whether the apparatus has been configured to preserve closed-field conditions beyond the separation step. If closed field conditions are to be maintained, as depicted in Fig. 13, the target collection vessel can be removed 1302 from the apparatus 1102 and the contents can be centrifuged 1304 without having to perform a vessel transfer. Next, supernatant fluid is removed 1306 from the vessel, preferably without having to invade the vessel or manually attach a receptical and cryomedia is added 1308. In some embodiments, heparin and/or human serum albumin (HSA) is added 1310. This is followed by a cryopreservation or cryotreatment step. In one embodiment, cryopreservation can include transfer to a freezing bag, preferably without the need to further invade the vessel or manually attach a receptacle. If substantially closed field conditions are not to be preserved, another procedure, depicted in Fig. 14 can be used. The procedure Fig. 14 includes many of the steps similar to those depicted in Fig. 10, including removing the vessel 1402, centrifuging 1406, aspirating 1406, adding cryomedia 1408, adding protein 1410 and cryopreserving 1412. However, in addition, the procedure of Fig. 14 includes the steps of opening the collection vessel 1403a and transferring from the collection vessel to a centrifuge tube 1403b. The procedure of Fig. 14 also includes a step of transferring from the centrifuge tube to a cryrovessel 1407. The opening and transferring steps 1403a, 1403b, 1407, in addition to defeating or seriously compromising the closed field condition, also require additional interventional steps, additional time and increase the possibility of error. The stirplate assembly further can include a position sensor for sensing when the column is positioned in the positioning portion of the stirplate assembly. In one embodiment, the position sensor further comprises a Hall effect sensor that is constructed for sensing changes in the magnetic field to thereby determine the position of the first and second magnets 1906 and 1908 and for providing a stirbar position signal to the data processor assembly, indicative of the sensed change in magnetic field. The cell separator permits substantially hands-free operation by a relatively unskilled operator. Ideally, the fluid bags, along with the tubing and column, are provided as disposable apparatus constructed for use during only a single separation process. Experimental Example A MicroKros syringe filter (Model X11M 100 2ON or X12M 100 20N, available from Microgon, Inc., Laguna Hills, CA 92653) was connected to a peristaltic pump, according to the manufacturer's directions. A suspension of CD34+ human hematopoietic stem cells (approximately 1 x 10 6 cells/mL in phosphate buffered saline (PBS), with or without 0.1% human serum albumin (HSA) was pumped through the syringe filter at a flow rate between about 10 and 20 mL/min. The cell suspension was continuously recirculated for between about 10 and 30 minutes, after which the volume reduction and cell recovery were calculated. As can be seen in Table III, a volume reduction between about 80% and about 90% could be achieved in about 15 minutes using this system, while recovering approximately 80% of the input cells. Shorter (9 minutes at 20 mL/min flow rate) and longer (25 minutes at 11 mL/min flow rate) recirculation times resulted in about the same percentage volume reduction, but substantially lower cell recoveries (about 64% to about 69%). Pore size (0.1 or 0.2 μ ) appeared to have little effect on % volume reduction or % cell recovery. Table III Unless otherwise indicated, input flow rates were 20 mL/min, cell concentration was about 1 x 10 6 cells/min, the starting volume of the cell suspension was 50 mL, and the cells were suspended in PBS without HSA. A number of variations and modifications of the depicted described invention can also be used. Although the cell washing apparatus and method was described in connection with washing of a suspension of cells and antibody material, cell washing procedure can be used in a number of other applications including e.g., removal of cryoprotectant solution after thawing and removal of nutritive medium after cell culture. As described above, the same apparatus can be used for washing a cell mixture and separating a cell mixture. In one contemplated application, a user would load the apparatus with tubing, hollow fiber device and sample bags and perform cell washing, as depicted in Fig. 3 and would then take the washed cells and use these as the sample 1004 for cell separation as depicted in Fig. 1 or in Fig. 2, preferably using the same apparatus but installing a new set of tubing and inserting a column 1002 in place of the hollow fiber device 3014. In another embodiment, it would be possible to construct another device which performed both operations, i.e., which conveyed the output of washed material from the valve 3014 directly to the input valves 1010 of a cell separator apparatus such as that in Fig. 1 or 2. Other types of fluid movement mechanisms than a peristaltic pump can be used, including gravity feed. Other separation devices than a column can be used, including ligand-coated plates or flasks (panning) or filtration. Those skilled in the art will appreciate that rotation of the magnet table 1904 results in rotation of the magnets 1906 and 1908 thereby creating a moving magnetic field. It will be apparent, however, that although the stirplate assembly is described herein as generating a moving magnetic field by rotating the first and second magnets and other apparatus, e.g., electromagnetic field generating apparatus, may be provided for generating a moving magnetic field. Further, as will become apparent below, it may be desirable in some applications to create the moving magnetic field by providing other motion to the field generating magnets, e.g., linear motion. Controlled stirrers other than magnetic stirrers can be used, including mechanically coupled stirrers, optically controlled stirrers and the like. Magnetically coupled stirrers can be provided with a drive mechanism other than a rotating magnet table such as electronically pulsed driving mechanism and could be provided with a relatively strong magnetic driving force to permit a relatively large distance between the bottom of the column and the drive mechanism so as to permit routing a conduit around the drive mechanism while avoiding cell loss from sharply curved or angled conduits. An agitation device such as that described with the outlet flow avoiding sharply curved flow paths can be used in connection with devices other than the cell separator such as a plasma phoreisis unit. Sharp curvature of the conduit can be avoided by a device other than tubing passing through the magnetic field such as using a rotary seal mechanism. Other types of digital controllers than those described can be used including optical controllers, fuzzy logic controllers, neural network controllers and the like. Controllers other than digital processor-based controllers can be used including application specific integrated circuits, discrete logic component circuits, analog circuits and the like. Concentration and pelletization can be performed by methods other than centrifuging including precipitation, sedimentation and filtration. Other types of conduit systems can be used including sterile docking devices, e.g., docking systems requiring splicing, such as the so-called "Hot knife" system available from Dupont and the "sterile connector" systems of Baxter Health Care. Although it is possible to use sterile docking systems which include splicing of conduits, it is preferable to use conduits such as the depicted tubing which can be provided in a fashion that does not require splicing by the user. Although embodiments described above include attachment of fluids systems such as a PBS bag, it is also possible to provide a system in which fluid systems such as PBS, HSA or anti-coagulant are provided pre-attached to a separation device, for example, as described in U.S. Patent No. 5,009,654. It is possible to use some described aspects of the invention without using others. For example, it is possible to use the closed-field aspect of the invention without using cryo-treatment. It is possible to provide the same vessel for collection and concentration without using a controller for controlling the operation of the apparatus. The apparatus can be used for separating cells other than human cells, e.g., eukaryotic cells such as plant cells and other animal cells and prokaryotic cells, such as bacteria. The apparatus can be used for separating particles, other than cells, e.g., liposomes, peptides and viruses. It will be apparent to those skilled in the art that although several embodiments of the invention have been described in detail herein, many modifications and variations may be provided without departing from the true scope and spirit of the invention. Accordingly, the invention is not limited except as by the appended claims.

Claims: WHAT IS CLAIMED IS: 1. A cell separation apparatus having a separation device assembly, the separation device assembly including a separation device for collecting target cells from a sample fluid contained in a sample container, and a fluid control system including a fluid collection vessel for receiving the target cells after being released from the separation device, said cell separation apparatus comprising: conduits coupling said separation device to said sample container and to said fluid collection bag to provide a pathway along which said target cells travel from said sample container to said separation device and from said separation device to said collection bag in the absence of exposure to the environment; means responsive to a valve control signal for selectively enabling the fluid coming out of the separation device to flow into the fluid collection vessel; and means for controlling the operation of the fluid control system, by providing said valve control signal. 2. An apparatus, as claimed in claim 1, wherein said pathway is provided as a closed field sterile pathway. 3. An apparatus, as claimed in claim 1, wherein said separation device is an immunoadsorption column. 4. An apparatus, as claimed in claim 1, wherein said separation device is a hollow fiber device. 5. An apparatus, as claimed in claim 1, wherein said means for controlling comprises a microprocessor. 6. A method for providing separated, concentrated particles from a solution containing said particles, comprising: providing said solution in a sample container, separated from the environment; providing a separation device, coupled to said sample container by at least a first conduit, said separation device having an interior separated from the environment; conveying at least a portion of said solution from said sample container to said interior of said separation device along said first conduit while maintaining said portion of said solution in a closed field condition in the absence of exposure of said portion of said solution to the environment; retaining at least some of said particles in said interior of said separation device to provide target particles in said separation device; providing a target vessel, coupled to said interior of said separation device by at least a second conduit, said target vessel having an interior separated from the environment; conveying a plurality of said target particles from said interior of said separation device to said collection vessel while maintaining said plurality of target particles in a closed sterile field condition in the absence of exposure of said plurality of target particles to the environment; and concentrating said target particles while maintaining said plurality of target particles in a closed sterile field condition. 7. A method, as claimed in claim 6, wherein said step of concentrating is performed without removing said target particles from said collection vessel. 8. A method, as claimed in claim 6, wherein said step of concentrating comprises conveying said particles to a hollow fiber device before conveying to said collection vessel. 9. A method, as claimed in claim 6, wherein said step of concentrating comprises centrifuging said plurality of target particles. 10. A method, as claimed in claim 6, further comprising: cryo-treating said plurality of target particles without removing said target particles from said collection vessel, to maintain said plurality of target particles in a closed field condition. 11. A fluid control system in combination with a cell separation device assembly, the device assembly including a column for collecting target cells from a sample fluid, the device assembly including a fluid collection vessel for receiving the target cells after being released from the column, said fluid control system comprising: a sensor which outputs a signal indicative of the optical density of fluid flowing out of the column and into the fluid collection vessel; valves responsive to a valve control signal to selectively enable the fluid coming out of the column to flow into the fluid collection vessel; a data processor which controls the operation of the fluid control system, said data processor responsive to said signal and outputting said valve control signal wherein inadequate concentrations of the target cells are prevented from being collected; and conduits, coupled to said cell separation device and said fluid collection vessel, forming a pathway along which said target cells travel from said cell separation device to said fluid collection vessel in the absence of exposure to the environment. 12. Apparatus of claim 11, further comprising a pump coupled to said conduit. 13. Apparatus, as claimed in claim 12, wherein said conduits provide a pathway from said column to said pump substantially in the absence of a sharp curvature of said pathway. 14. Apparatus, as claimed in claim 11, further comprising a magnetic stirrer driver having a slot therein for accommodating said conduit. 15. A fluid control system in combination with a cell separation device, the cell separation device including a column for separating target cells from a sample fluid held in a sample container, the cell separation device assembly including a fluid collection vessel for receiving the target cells after being released from the column, said fluid control system comprising: sensor means for providing a signal indicative of the optical density of fluid flowing out of the column and into the fluid collection vessel; valve means responsive to a valve control signal for selectively enabling the fluid coming out of the column to flow into the fluid collection vessel; data processor means for controlling the operation of the fluid control system, said data processor means being responsive to said signal for providing said valve control signal to prevent inadequate concentrations of the target cells from being collected; and means, coupling said column on said sample fluid and to said fluid collection vessel, for providing a pathway along which said target cells travel from said sample container to said column and from said column to said vessel in the absence of exposure to the environment. 16. A method for contamination-free, repeatable particle separation comprising: a) providing a particle separation device having a separation column receptacle and a plurality of controllable valves; b) providing a separation device, and said separation device having an inlet port and an outlet port; c) mounting at least first and second conduits, coupled to said inlet and outlet ports, respectfully in operable proximity to said controllable valves to permit selective opening and closing of said conduits; d) coupling said conduits to at least a sample source and a target collection vessel; e) controlling said controllable valves to convey contents of said sample source to said separation device wherein at least a first plurality of target particles are separated in said separation device; f) controlling said controllable valves to convey said first plurality of target particles to said collection vessel; g) removing said sample source, said conduits, said separation device and said collection vessel; h) repeating steps b) through g) , using a different sample source, conduits, separation device and collection vessel to separate a second plurality of target particles in the absence of contamination by said first plurality of target particles or by the contents of a previous sample source. 17. A method, as claimed in claim 16, wherein said step of providing a separation device includes coating the interior and contents of said separation device with a protein, prior to said step of mounting said separation device. 18. A method, as claimed in claim 16, wherein said steps of mounting and repeating are performed substantially in the absence of splicing said conduits. 19. A method, as claimed in claim 16, wherein said separation device comprises an affinity-specific substrate. 20. A method, as claimed in claim 16, wherein said separation device comprises a hollow fiber device. 21. A cell separation apparatus having a separation device assembly, the separation device assembly including a separation device for separating target cells from a sample fluid contained in a sample container, and a fluid control system including a collection vessel for receiving the target cells, said cell separation apparatus comprising: a cell concentrator means for increasing the volume concentration of said target cells; conduits coupling said separation device to said sample container and to said fluid collection bag to provide a pathway along which said target cells travel from said sample container to said separation device, from said separation device to said cell concentrator means and from said cell concentrator means to said collection vessel; means responsive to valve control signals for selectively enabling the fluid coming out of the separation device to flow to said cell concentrator means and for selectively enabling the target cells coming out of said cell concentrator means to flow into the fluid collection vessel; and means for controlling the operation of the fluid control system, by providing said valve control signals. 22. A cell separation apparatus, as claimed in claim 21, wherein said cell separator means comprises a hollow fiber device having a plurality of hollow fibers defining a plurality of fiber lumens configured to convey said target cells through said lumens. 23. A cell separation apparatus, as claimed in claim 21, wherein said hollow fibers are formed from a membrane and further comprising means for withdrawing fluid through the membrane of said hollow fibers. 24. A cell separation apparatus, as claimed in claim 23, wherein said means for withdrawing comprises means for forming a trans-membrane pressure differential. 25. A cell separation apparatus, as claimed in claim 21, wherein said conduits provide a substantially closed field pathway. 26. A cell separation apparatus, having a separation device for separating target cells from a mixture of target cells and other material, the apparatus comprising: a sample container for holding said mixture of target cells and other material; said separation device being coupled to said sample container to receive said mixture and output a first suspension of target cells and a fluid, said first suspension having a first concentration of target cells; a hollow fiber device, coupled to said separation device, to receive said first suspension and output a second suspension, having a second concentration of target cells greater than said first concentration. 27. An apparatus, as claimed in claim 26, wherein said separation device is an immunoadsorption column. 28. An apparatus, as claimed in claim 26, wherein said apparatus provides a substantially closed field pathway from said sample container to said hollow fiber device. 29. An method for providing separated, concentrated particles from a solution containing said particles, comprising: providing said solution in a sample container; providing a separation device; conveying at least a portion of said solution from said sample container to said separation device; retaining at least some of said particle in said separation device, to provide target particles; conveying said target particles from said separation device to a hollow fiber device; and, concentrating said target particles in a hollow fiber device. 30. A method, as claimed in claim 29, wherein said steps of conveying at least a portion of said solution, retaining, conveying said target particles and concentrating are performed while maintaining substantially closed-field conditions. 31. A cell washing apparatus, for washing cells contained in a sample container with a wash fluid, contained in a wash container, and conveying to a collection vessel, comprising: a hollow fiber device having a plurality of hollow fibers formed of a porous membrane, said fibers defining lumens having a first end and a second end, said hollow fiber device having an inlet port for providing material to said first end of said lumens of said hollow fibers, a first outlet port for withdrawing material from said second end of said lumens of said hollow fibers, and a third port for withdrawing material after passage through said porous membrane; conduits coupling said first port of said hollow fiber device to said sample container and said wash container, and coupling said second port to said collection vessel, in the absence of exposure to the environment; means, responsive to a valve control signal, for selectively enabling the fluid coming out of hollow fiber device to flow into said collection vessel; and means for providing said valve control signal to control fluid flow out of said hollow fiber device. 32. Apparatus, as claimed in claim 31, further comprising a recycling conduit for conveying material withdrawn from said second port for provision to said first port. 33. Apparatus, as claimed in claim 32, responsive to a valve control signal, for selectively enabling the fluid coming out of said hollow fiber device to flow into said recycling conduit. 34. A cell washing apparatus, for washing cells contained in a sample container with a wash fluid, contained in a wash container, and conveying to a collection vessel, comprising: a hollow fiber device having a plurality of hollow fibers formed of a porous membrane, said fibers defining lumens having a first end and a second end, said hollow fiber device having an inlet port for providing material to said first end of said lumens of said hollow fibers, a first outlet port for withdrawing material from said second end of said lumens of said hollow fibers, and a third port for withdrawing material after passage through said porous membrane; conduits coupling said first port of said hollow fiber device to said sample container and said wash container, and coupling said second port to said collection vessel, in the absence of exposure to the environment; valves, responsive to a valve control signal, effectively opening and closing conduits coupling said hollow fiber device to said collection vessel; and a computer which outputs said valve control signal. 35. A method for washing and separating particles, mixed with other material, in a contamination-free manner, comprising: a) providing a base having a first receptacle and a plurality of controllable valves; b) positioning a hollow fiber device having an inlet port, a first outlet port and a second outlet port, in said receptacle; c) mounting at least first and second conduits, coupled to said inlet port and said first and second outlet ports, in operable proximity to said controllable valves to permit selective opening and closing of said conduits; d) coupling said conduits to at least a sample source, a wash source, an intermediate collection vessel and a waste vessel; e) controlling said controllable valves to convey contents of said sample source to said separation device wherein at least a first plurality of target particles are conveyed through said hollow fiber device to said first outlet port and at least some of said other materials are conveyed to said second outlet port; f) controlling said controllable valves to convey the output of said first outlet port to said intermediate collection vessel g) removing at least said sample source and said hollow fiber device from said base; h) positioning a separation device having an affinity-specific substrate, on said base, said separation device having an inlet port and said outlet port; i) coupling said intermediate collection vessel to said inlet port of said separation device, and coupling a final collection vessel to said outlet port of said separation device; j) controlling said controllable valves to convey contents of said intermediate collection vessel to said separation device, wherein at least a first plurality of target particles are retained in said separation device; k) controlling said controllable valves to convey said first plurality of target particles to said final collection vessel. 36. A method, as claimed in claim 35, further comprising: providing conduit coupling the first outlet port of said hollow fiber device to said first inlet port of said hollow fiber device; and controlling said controllable valves to convey the output from said first outlet port of said hollow fiber device to the inlet port of said hollow fiber device. 37. A collection vessel system for maintaining closed field conditions during concentration and transfer of particles, comprising: a rigid-walled vessel defining a vessel interior, having a plurality of ports, said vessel being substantially sealed from the environment; a first conduit, coupled to a first port, for i conveying said particles into said vessel; a second vessel permanently coupled to said rigid- walled vessel by a second conduit; and a third vessel permanently coupled to said rigid- walled vessel by a third conduit. 38. A collection vessel system, as claimed in claim 37, wherein said second and third vessels, are flexible-walled bags. 39. A collection vessel system, as claimed in claim 37, further comprising clips for selectively opening and closing said second and third conduits. 40. A centrifuge cup comprising: a base member; a first recess, formed in said base member, configured to hold a first rigid-walled vessel; and a second recess, different from said first recess, configured to hold at least a first empty vessel, coupled to said first rigid-walled vessel. 41. A centrifuge cup comprising: a base member; first means for holding a first rigid-walled vessel; second means for holding an empty vessel, coupled to said rigid-walled vessel, said second means being different from said first means. 42. A method for concentrating particles in closed field conditions, comprising: providing first, second and third vessels, said first and second vessels coupled by a first conduit, said second and third vessels coupled by a second conduit; receiving said particles, mixed with a fluid, in said first vessel; centrifuging said first, second and third vessels, simultaneously; closing said second conduit; pouring at least some of said fluid, through said first conduit into said second vessel; opening said second conduit; and transferring said particles to said third vessel, using said second conduit. 43. Apparatus for freezing cells, comprising: a flexible walled bag for containing said cells, said bag having a first pocket for retaining identifying information; a freezing cassette having a first platform for supporting said flexible walled bag in a freezing position and a cover having a first window, said cover for covering substantially all of said freezing bag, in cooperation with said platform, except for said pocket, said window being substantially aligned with said pocket when said freezing bag is in said freezing position, to provide for visibility of said identifying information.

Inventors: CORPUZ STANLEY, EMDE MICHAEL D, HEIMFELD SHELLY, KALAMASS DALE, MALONEY PATRICK M, MILL FRED, MINSHALL BILLY W, PETERSON ERIC, THOMPSON PENNY, CORPUZ, STANLEY, EMDE, MICHAEL, D., HEIMFELD, SHELLY, KALAMASS, DALE, MALONEY, PATRICK, M., MILL, FRED, MINSHALL, BILLY, W., PETERSON, ERIC, THOMPSON, PENNY
Applicants: CELLPRO INC, CELLPRO INCORPORATED
Application year: 1994
Main classification: G01N21
IPC codes: A61M1, B01D61, B01D63, B01F13, B01F15, B01L3, C12M1, G01N1, G01N11, G01N33, G01N35